Maximum Tolerable Dose (MTD)

2016 ◽  
Author(s):  
J. H. Duffus
Author(s):  
Jerzy Karczewski ◽  
Christine M Brown ◽  
Yukari Maezato ◽  
Stephen P Krasucki ◽  
Stephen J Streatfield

Abstract Objectives To evaluate the efficacy of a novel lantibiotic, CMB001, against MRSA biofilms in vitro and in an in vivo experimental model of bacterial infection. Methods Antibacterial activity of CMB001 was measured in vitro after its exposure to whole blood or to platelet-poor plasma. In vitro efficacy of CMB001 against a Staphylococcus aureus biofilm was studied using scanning electron microscopy. The maximum tolerable dose in mice was determined and a preliminary pharmacokinetic analysis for CMB001 was performed in mice. In vivo efficacy was evaluated in a neutropenic mouse thigh model of infection. Results CMB001 maintained its antibacterial activity in the presence of blood or plasma for up to 24 h at 37°C. CMB001 efficiently killed S. aureus within the biofilm by causing significant damage to the bacterial cell wall. The maximum tolerable dose in mice was established to be 10 mg/kg and could be increased to 30 mg/kg in mice pretreated with antihistamines. In neutropenic mice infected with MRSA, treatment with CMB001 reduced the bacterial burden with an efficacy equivalent to that of vancomycin. Conclusions CMB001 offers potential as an alternative treatment option to combat MRSA. It will be of interest to evaluate the in vivo efficacy of CMB001 against infections caused by other pathogens, including Clostridioides difficile and Acinetobacter baumannii, and to expand its pharmacokinetic/pharmacodynamic parameters and safety profile.


2017 ◽  
Vol 19 (suppl_6) ◽  
pp. vi78-vi78
Author(s):  
Maria Guerra Garcia ◽  
Beth Goins ◽  
Aleksandra Gruslova ◽  
Michael Garcia ◽  
Andrew Brenner

2021 ◽  
Vol 9 ◽  
Author(s):  
Mariyah Pressley ◽  
Monica Salvioli ◽  
David B. Lewis ◽  
Christina L. Richards ◽  
Joel S. Brown ◽  
...  

Rapid evolution is ubiquitous in nature. We briefly review some of this quite broadly, particularly in the context of response to anthropogenic disturbances. Nowhere is this more evident, replicated and accessible to study than in cancer. Curiously cancer has been late - relative to fisheries, antibiotic resistance, pest management and evolution in human dominated landscapes - in recognizing the need for evolutionarily informed management strategies. The speed of evolution matters. Here, we employ game-theoretic modeling to compare time to progression with continuous maximum tolerable dose to that of adaptive therapy where treatment is discontinued when the population of cancer cells gets below half of its initial size and re-administered when the cancer cells recover, forming cycles with and without treatment. We show that the success of adaptive therapy relative to continuous maximum tolerable dose therapy is much higher if the population of cancer cells is defined by two cell types (sensitive vs. resistant in a polymorphic population). Additionally, the relative increase in time to progression increases with the speed of evolution. These results hold with and without a cost of resistance in cancer cells. On the other hand, treatment-induced resistance can be modeled as a quantitative trait in a monomorphic population of cancer cells. In that case, when evolution is rapid, there is no advantage to adaptive therapy. Initial responses to therapy are blunted by the cancer cells evolving too quickly. Our study emphasizes how cancer provides a unique system for studying rapid evolutionary changes within tumor ecosystems in response to human interventions; and allows us to contrast and compare this system to other human managed or dominated systems in nature.


2021 ◽  
Vol 17 ◽  
Author(s):  
Shruthi Suresh ◽  
Srikanth Raghavendran ◽  
Stalin Selvaraj

: Conventional cancer therapy kills tumors by applying the maximum tolerable dose of therapy. However, it leads to the development of tumoral heterogeneity and resistance, hence leading to therapy failure and progression. It is necessary to design therapies keeping in mind the evolutionary dynamics of tumors to minimize resistance and delay progression. Mathematical models are of great importance in oncology as they assist in the recreation of the tumor microenvironment, predict the outcomes of treatment strategies and elucidate fundamentals of tumor growth and resistance development. The body of literature covering models which incorporate evolutionary dynamics is vast. This paper provides an overview of existing models of “evolutionary therapy”, including ordinary differential equations, fitness, and probability functions.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1971-1971
Author(s):  
Wolfram Pönisch ◽  
Simone Heyn ◽  
Ina Wagner ◽  
Martin Mohren ◽  
Franz-Albert Hoffmann ◽  
...  

Abstract Abstract 1971 Introduction: While the role of lenalidomide monotherapy in the treatment of relapsed/refractory patients with multiple myeloma (MM) is established, combination therapies with Lenalinomide are still under investigation. Bendamustine is a bi-functional alkylating agent with a purine-like benzimidazole ring effective in combination with steroids, thalidomide and bortezomib for the treatment of patients with MM. In the current trial, combination therapy of bendamustine, lenalinomide and prednisolone (RBP) was tested for feasibility and safety in patients with relapsed or refractory MM. Patients and Methods: This is a phase I trial examining dosing of lenalidomide in combination with bendamustine and prednisolone. The first cohort of patients received a starting dose of 10mg/d d1-21 lenalidomide, 60mg/m2/d d1-2 bendamustine and 100mg/d d1-4 prednisolone. Escalation steps in the next cohorts included 15, 20 and 25mg of lenalidomide followed by an escalation step of 75 mg/m2 bendamustine. Three patients were enrolled at each dose level and the first two cycles were evaluated for maximum tolerable dose. Patients received RBP in 4-week cycles for a maximum of 8 cycles in order to evaluate efficacy. Patients with stable or responding disease following 8 cycles of RBP received single-agent oral lenalidomide 10 mg once daily on days 1–21 of each 28-day cycle as maintenance. Results: : Nine patients (3 at each dose level of 10 mg, 15 mg or 20 mg lenalidomide) have been enrolled to date and 9 patients have completed at least 2 cycles. Response was assessed using modified EBMT criteria to include near complete remission (nCR) and very good partial remission (VGPR). 8 of 9 patients responded after at least 2 cycles with 2 VGPR, 4 PR, 1 MR and 1 stable disease. One patient experienced progressive disease. None of the 9 patients developed dose-limiting hematoxicity as defined by an ANC < 1,0 × 109/l with fever for > 3 days or an ANC <0,5 × 109/l for > 7 days or platelet count < 25 × 109/l for > 3 days. Neutropenia was reported in 4 patients (CTC grade ≥ 3) but no thrombocytopenia (CTC grade ≥ 3) was observed. No grade 3 or 4 non hematological toxicity was encountered and no dose modification was required. Conclusions: RBP with a dose of 20 mg lenalidomide d 1–21 and 60 mg/m2 bendamustine d 1–2 is well tolerated in patients with relapsed or refractory MM. Maximum tolerable dose was not reached. Further dose increase according to the protocol is in progress. Disclosures: Niederwieser: Bristol-Myers Squibb: Speakers Bureau; Novartis: Speakers Bureau.


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